The invention relates generally to modulated carrier wave communication devices, and more particularly, to communication method, apparatuses, and systems using electrical or electromagnetic signals transmitting an intelligence bearing signal from one point to another in the form of discrete variations in some parameter of the electrical or electromagnetic signal, used in conjunction with position location methods, apparatuses, and systems of the type in which a position is determined from a constellation of satellites.
Many different types of wireless systems for communications exist, such as cellular networks for telephone communication, broadband Personal Communication Services (PCS), wireless local-area networks (LANs), satellite communication systems, and two-way radio systems. Typically, these wireless systems include fixed infrastructure, having one or more communication devices, and remote units that may be either fixed or mobile. Examples of mobile remote units, also called mobile stations (MS), include cellular telephones, satellite telephones, wireless communication enabled personal computers, personal digital assistants (PDA), and other wireless devices. Fixed remote units can include, for example, wireless local loop (WIL) stations.
Typically, the infrastructure of a wireless system includes one or more base station (BTS) units at fixed positions that communicate with the MSs. The base stations may also communicate with fixed remote units, each other, or an external network.
In many situations, it is desirable to determine the position of a mobile MS. For example, many location-based services (LBS) communicate particular information to an MS user based on the location of the MS. For example, an LBS may provide an MS user with driving directions to a destination identified by the user, based on the user's location. Or an LBS may provide information about a current sales promotion if the user is located in close proximity to a store where the sale is taking place. Other LBSs include gaming, security, and fleet management.
Another motivation for determining the location of an MS is to support wireless carriers in complying with a U.S. Government Federal Communications Commission (FCC) regulation that requires carriers in the United States to be able to locate the position of a cellular telephone making an emergency “911” call within 50 meters for 67 percent of such calls and within 150 meters for 95 percent of such calls.
Different approaches to obtaining a position solution can be implemented to determine the geographic position of an MS in a communication system. The relative performances of the different approaches, as applied to any particular MS and type of wireless communications system, will depend, at least in part, on characteristics of the geographic region where the MS is located. Therefore, it would be desirable to select a position solution based on the performance of the position solution in the environment in which the MS is located. There is a need for a method and apparatus that can select a position solution approach.